Ingot mold with opposed exothermic sideboards

ABSTRACT

921,274. Ingot moulds. FOSECO INTERNATIONAL Ltd. Aug. 23, 1960 [Dec. 3, 1959], No. 29160/60. Class 83 (1). An ingot mould for casting killed steel, and particularly a big-end down mould, 10 has a hot top comprising two slabs 18 of heat-producing material held in spaced-apart relation and tightly against the side walls, as by rods 46 or wedges 54, or both. A device 25 for inserting the slabs comprises a member 26 with depending partitions 28, 29, 30, and engages on top of the slabs by shoulders 36. Vertically slidable U- pieces 39 hold the device between the pair of slabs and move upwardly as the slabs enter the mould. The wedging rods 46 are releasably supported in slots in shafts 48 which are rotated by means engaging their ends 50 when the slabs are in position, to wedge the rods between the slabs. The device 25 is then removed upwardly, the rods 46 disengaging from the shafts 48. A granular heat-producing material may be added to the top of the melt. Specification 627,678 is referred to.

March l1, 1969 H. D. sHEPHARD, JR., ETAL 3,432,138

INGOT MOLD WITH OPPOSED EXOTHERMIC SIDEBOARDS Filed Sent. 8 1959 UnitedStates Patent O 3,432,138 INGGT MOLD WITH OPPOSED EXOTHERMIC SIDEBOARDSHarry D. Shephard, Jr., Pittsburgh, Pa., and Norman J. Griflths,deceased, late of Vanderbilt, Pa., assignors, by mesne assignments, toFoseco, Inc., Cleveland, Ohio, a corporation of New York Filed Sept. 8,1959, Ser. No. 13,673 U.S. Cl. 249-106 Int. Cl. B22d 7/10 The presentinvention relates to the production of steel and more particularly tothe casting of killed steel in big end down ingot molds. This inventionfurther relates to an improved apparatus for hot topping ingot moldsfinding particular but not exclusive use in the production of lled steelingots.

Killed steel ingots for use in the manufacture of wide sheet steel haveconventionally been cast in either of two ways: 1) in big end up moldsusing one of the conventional methods of hot topping such as clay hottops or refractory lined cast metal hot tops; (2) in big end down moldswithout any hot tops at all. The use of big end down molds for thecasting of ingots has a substantial advantage with respect to handlingof the ingots and removal of the molds from them.

When using a big end down mold for killed steel without a hot top alarge primary pipe cavity is left in the top of the ingot as a result ofthe normal shrinkage of the steel. In this practice, the average primesteel yield is somewhere in the neighborhood of 72 to 73%. Generallyonly 76% of an ingot made by this practice can be considered sound, andafter a 4% crop from the bottom of the ingot the prime yield is reducedto about 72% for the manufacture of Wide sheet steel.

14 Claims When using a big end up mold with a conventional hot top, ahot top volume of about 14% excess steel is necessary to produce a soundbody in the ingot. With the normal 4% bottom crop an average yield ofabout 82% is obtained with the hot topping practice. As mentioned above,however, the big end up hot topped ingot procedure is subject `to asubstantial disadvantage when it comes to handlingand removing the ingotfrom the mold. The hot top must be removed and the mold must beinverted, both of which steps require extra handling procedures.

It is the primary object of the present invention to provide an improvedhot topping for ingot molds. More specifically, it is an object toprovide an improvement of the foregoing type which finds particular usein the hot topping of big end down open top slab ingot molds.

Another object of the present invention is to hot top big end down opentop ingot molds without using a separate hot top casting or the like.Still another object is to hot top a mold in a manner which is simpleand economical and which at the same time increases the yield of soundingots cast.

A further object of the present invention is to provide a hot toppingfor ingot molds of the foregoing character in order to add suflicientheat to the ingot mold to enable fully killed steel to be cast therein.More specifically, it is an object of the invention to provide animprovement of the foregoing character by which heat is added to theingot mold, and the cross sectional area of the mold top is reduced toform a feeder head. A related object is to cast killed steel ingots inwhich a single step continuous pour can be employed.

3,432,138 Patented Mar. 11, 1969 A more specific object of the presentinvention is to mount slabs of exothermically reacting material inposition within the mouth of a lbig end down open top ingot mold for useas a hot top when casting fully killed steel.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds taken in connection withthe accompanying drawings wherein:

FIGURE 1 is a perspective view of a big end down ingot mold the upperopen end of which is hot topped in accordance with the presentinvention.

FIG. 2 is a perspective View of a slab or side board of a refractorybacked exothermically reacting material suitable for mounting in aningot mold of the type shown in FIG. l.

FIG. 3 is a fragmentary plan view of the ingot mold shown in FIG. 1.

FIG. 4 is a Vertical section view ot' the upper end of the ingot mold ofFIG. 1 and illustrating slabs of exothermically reacting material, ofthe type shown in FIG. 2, mounted within the open mouth of a big enddown ingot mold.

While a certain illustrative method and modified form of apparatus havebeen shown in the drawings and will be described below in considerabledetail, it should be understood that there is no intention to limit theinvention to the specific method or apparatus shown and described. Onthe contrary, the intention is to cover al1 modifications, alternativeconstructions, equivalents and uses falling within the spirit and scopeof the invention as expressed in the appended claims.

The present invention finds particular, but not exclusive utility forcasting ingots of killed and semi-killed steel. The distinctions betweenkilled, semi-killed, rimmed and capped steel are described in detail inThe Making, Shaping and Treating of Steel, 6th ed., United States SteelCo., Pittsburgh, Pa. (1951). So far as the discussion of ingot castingand types of ingot structure pertain to this invention, the disclosurein this book is incorporated herein by reference.

Briefly, a killed steel ingot is produced by casting into an ingot molda steel having a uniformly low level of oxygen content. This isconventionally done by deoxidizing the steel sufficiently so that themetal lies perfectly quiet when poured into an ingot mold and there isno evolution of gas from the mold. The shrinkage of metal which occurson solidication causes a slightly concave top and large cavities belowthe top often separated by bridges. The cavities and concave toptogether constitute what is termed pipe In conventional practice, killedsteels are usually poured into hot topped molds of the big end up typeor into big end down molds which are not hot topped. An illustrative bigend down open top mold is shown in U.S. Patent 2,871,532, issued Feb. 3,1959 to M. H. Gathmann.

The present invention is concerned with hot topping ingot molds andfinds particular but not exclusive utility for hot topping big end downopen top ingot molds for use in casting ingots of killed steel.Referring to FIG. 1 of the drawings, an ingot mold of this type is thereshown which comprises a mold 10 supported on a stool 11. The mold isgenerally rectangular or oblong in shape, having two long side walls 14and two short end walls 1S defining a mold cavity. The interior wallsurfaces of the mold may have Vertical corrugations 16 therein. Theinner walls of the mold taper downwardly and outwardly and the walls ofthe mold are generally thicker at the bottom than at the top.

In accordance with the present invention, there is supported within theopen mouth of the mold, along the two long sides 14 thereof, a pair ofslabs or side boards 18 of heat producing exothermically reactingmaterial. These slabs 18 are held apart so that they rest tightlyagainst the inner surface of the side walls 14 of the mold. It has beenfound that the shorter end walls of the mold need not be covered with aslab of heat producing material.

The heat producing slab is preferably a composite slab (FIG. 4)comprising a layer 19 of a refratcory backing material and a layer 2)`of a moldable exothermically reacting substance.

One illustrative moldable exothermically reacting composition which maybe employed is disclosed in U.S. Patent 2,591,105. Compositions producedas described in this patent are available under the trademark Feedexfrom Foundry Services, Inc. of Cleveland, Ohio.

The exothermically reacting material described therein is a compositionformed of an oxidizable metal such as aluminum with an oxidizer such asiron or manganese oxide in an amount substantially less than that amountrequired to react stoichiometrically with, that is, cornpletely oxidize,the aluminum. The composition also contains a fluoride compound tofacilitate the start of the reaction (upon contact with molten metal)and to facilitate maintaining the reaction to completion. The patentgives the following composite range and a preferred cornposition for usewith steel castings:

1 Remainder.

For a more detailed description of such exothermically reacting materialreference should be made to Patent No. 2,591,105.

The slabs are prepared in any suitable manner. For example, a slab maybe constructed by first placing in a suitable mold a granular refractorymaterial such as a sand or refractory grog mixed with a suitable binder.The configuration of the bottom of the mold is preferably the same asthat of the ingot mold wall to which the slab will be applied. Thus ifthe ingot mold walls are corrugated, the refractory layer should be soformed as shown in FIG. 2. Appropriate steel reinforcing frames 21 (asshown in FIG. 4) are inserted into the refractory and a plurality ofhooks or eyes 22 are mounted therein so as to extend from onelongitudinal edge of the slab thereof. The refractory is hardened, atleast partially, and then a layer of the above described exothermicallyreacting material is placed therein. The entire slab is then fired at atemperature below that which will cause the exothermically reactingmaterial to ignite but high enough to set the binder. Alternatively, acold process binder such as a CO2 gas hardenable silicate binder may beemployed.

For purposes of holding the slabs apart and tightly against the moldwalls so as to prevent molten metal from flowing between the slabs andthe mold wall, a pair of low carbon steel bars 46 are wedged tightlybetween their opposing faces as shown in FIG. 4.

The bar 46, which is slightly longer than the spacing between the heatproducing slabs, is wedged tightly between the heat producing layers asshown in FIG. 4. To facilitate the wedging of the bars 46 between theslabs 18, they are desirably shaped like a shollow S or have their endsslightly curved or rounded. The bars 46 shown in FIG. 3 are S-shaped,and can be readily wedged into place by rotation in a counter-clockwisedirection.

Because the bars 46 remain in the hot top and are melted or otherwiseremain in the steel, the bars are preferably formed of a low carbonsteel material which will not adversely affect the killed steel beingcast.

In order to prevent the buoyant force of the metal from lifting theslabs, wooden wedges 5()` are driven at each slab corner between theslab and the end wall of the mold (FIG. l). Further support for the heatproducing slabs 18 is provided by the use of additional cross rods 52which are like the previously inserted rods 44. These additional rodsmay be inserted through corresponding ones of the remaining hooks 22which project from the upper edge of the slabs. These additional crossrods 52 rest on the upper end of the ingot mold as shown in FIG. 1 andafford support for the slabs during the pouring of the metal.

A mold in condition for receiving molten metal, which is hot topped inaccordance with the present invention, is shown in FIG. l. During theteeming of molten metal into the ingot mold, the pourer should slow upbut need not stop when reaching the bottom of the slabs 18. After thehot top is filled, the top of the ingot is conventionally covered with agranular insulating or heat producing substance such as a Thermitesubstance or the materials described, for example, on page 516 of theabove mentioned book The Making, Shaping, and Treating of Steel. Thisadded substance reduces or eliminates radiation and loss of heat fromthe open top of `the mold. Additional heat producing material can beadded when needed if necessary to keep the top of the ingot molten.

As the molten metal reaches the heat producing slabs 18 during the pour,the temperature of the metal ignites the exotherrnically reactingmaterial 20. This material continues to burn after the pour is completedand adds a substantial amount of heat to the upper end of the mold. Asthe molten metal in the mold solidies, the hotter upper portion servesas a feeder head and thereby fills the pipe or cavity within the ingot.

In order to provide a sloping tapered shoulder on the ingot between themain body and the hot top portion thereof, a construction which isdesirable when the ingot is to be used in certain rolling and forgingoperations, the lower edge 55 of each slab 18 (as shown in FIG. 4) istapered downwardly and outwardly. Such a taper in the completed ingotfacilitates rolling and reduces the amount of crop which must be takenfrom the ingot.

In accordance with another aspect of the present invention, ingots whichare approximately square in cross section and smaller than the slabingots discussed above can be hot topped in a similar manner. When theseingots are hot topped with only two opposed slabs or side boards of heatproducing material, we have found that surprisingly economical resultsare obtained. The ingots produced are sound in that the hot top does aneflicient job of feeding molten metal as the ingot shrinks.

When carrying out this aspect of the present invention, a generallysquare ingot is hot topped by lowering into the mouth of the mold a pairof slabs of heat producing material in much the same manner as describedabove. These slabs, constructed in the sa-me manner -as slabs 1S asshown in FIG. 2, are supported from the mouth of the ingot by cross rodsas shown in FIG. 1, and are positioned against opposed side walls of themold. The slabs are held in place by wooden wedges such as the wedges S0shown in FIG. 1, and spreader rods such as the S- shaped rods 46 may beemployed. We have found, however, that in the smaller size square lingotmolds, the

wooden wedges serve to prevent the slabs from lioating on the moltenmetal and accomplish the purpose of holding the slabs apart and tightlyagainst the mold walls. For example, a conventional ingot mold has a 23inch x 24 inch cavity. Opposed heat producing slabs are suspended withinthe open mouth of the ingot cavity `by rods, such as the rods 44 throughthe loops 22, are

held up against opposite side Walls of the mold, and are wedged intoplace by wooden wedges driven between the ends of the slabs and theadjacent mold end walls.

As pointed out above, it is usually desirable to add a granular heatproducing material onto the top of molten metal after it has been pouredinto the mold. This substance not only supplies additional heat to themold but also serves as an insulating cover for the mold.

We claim as our invention:

1. In combination, a rectangular ingot mold having opposed side wallsand relatively shorter end walls dening a mold cavity, and a pair ofslabs of heat producing material suspended with-in the mold cavity andwedged in opposed relation against the mold side walls and between theopposed mold end walls which remain substantially bare, said slabs andsaid bare mold end walls defining a hot top cavity which is smaller incross section than the mold cavity.

2. In combination, a rectangular ingot mold having opposed side wallsand relatively shorter end walls delining a mold cavity, and a pair ofslabs of refractory backed exothermically reacting material suspendedwithin the mold cavity and wedged in opposed relation against the moldside walls and between the opposed mold end walls which remainsubstantially bare, said slabs and said bare mold end walls defining ahot top cavity which is smaller in cross section than the mold cavity.

3. In combination, a rectangular ingot mold having side walls andrelatively shorter end walls defining a mold cavity, a pair of slabs ofheat producing material suspended within the mold cavity and adjacenttwo opposed side walls only of the mold, and means wedging said slabs inposition against said two side Walls and between the adjacent opposedend walls, thereby leaving the latter walls substantially bare, saidslabs and said bare mold end walls defining a hot top cavity which issmaller in cross section than the mold cavity.

4. In combination, a slab ingot mold having vertical spaced side Wallsand adjacent shorter end walls, a pair of opposed slabs of heatproducing material lining only an upper portion of said side Walls andextending between said end walls which remain substantially bare, meanssupported on the upper end of said mold walls suspending said slabswithin the mold, means holding said slabs in spaced apart relation andtightly against said mold side walls, and wedge means wedged betweensaid end walls and said slabs f0.1` preventing said slabs from beingraised out of the mold when molten metal is teemed therein, said slabsand said bare mold end walls defining a hot top cavity which is smallerin cross section than the mold cavity.

`5. In combination, an ingot mold for casting metal having verticalspaced side and end walls, opposed slabs of heat producing materiallining only an upper portion of said side walls and extending betweensaid end walls which remain substantially bare, said slabs comprising alayer of refractory heat insulating material and a layer ofexothermically reacting material, and non-heat producing means holdingsaid slabs in spaced apart relation and tightly against said side walls,thereby defining with said end walls a feeder head space, said holdingmeans including a rod wedged between opposed surfaces of exothermicallyreacting material of said slabs.

6. In combination, a slab ingot mold having vertical spaced side wallsand adjacent shorter end walls, opposed slabs of heat producing materiallining only an upper portion of said side walls and extending betweensaid end walls which remain substantially bare, said slabs comprising alayer of refractory heat insulating material having a recess defined inone surface thereof and a layer of exothermically reacting material insaid recess, means vertically supporting said slabs within said mold,and means holding said slabs in spaced apart relation and tightlyagainst said walls, said slabs defining with said end walls a feederhead space, said holding means including a non-heat producing meanswedged between opposed surfaces of exothermically reacting material ofsaid slabs and wedge means wedged between said end walls and therefractory edges of said slabs for preventing said slabs from beingraised out of the mold when molten metal is teemed therein.

7. An ingot mold having an open end mold cavity for casting metalingots, means for increasing ingot yields comprising, a pair ofsubstantially exothermic side boards secured to said ingot mold alongopposed inner surfaces of the upper portion of the mold cavity and onopposite sides of the pouring area of the mold, and bare surface areason the inner surface of the mold between said side boards.

8. In combination, a rectangular ingot mold having vertical spaced sideand end walls, a pair of opposed slabs of heat producing material liningonly an upper portion of said side walls and extending between the endwalls which remain substantially bare, means supported on the upper endof the mold for suspending said slabs in the mold, and means holdingsaid slabs in spaced apart relation and tightly against said mold sidewalls, said slabs and said bare mold end walls defining a hot top cavitywhich is smaller in cross section than the mold cavity.

9. An ingot mold having an open end mold cavity for casting metalingots, means for increasing ingot yields comprising, a pair ofsubstantially exothermic side boards positioned within said ingot moldalong opposed inner surfaces of the upper portion of the mold cavity andon opposite sides of the pouring area of the mold, and bare surfaceareas on the inner surface of the mold between said side boards.

10. In an ingot mold having an upwardly opened mold cavity -for castingmetal ingots, a pair of exothermic side members positionably retained inthe mold on opposite sides of the feed zone of said mold cavity, each ofsaid members engaging a separate side board having a surface whichengages and complements the inner surface of the mold cavity, and baresurface areas -on the inner surface of the mold between said sideboards.

11. The ingot mold of claim 7 wherein Vsaid mold cavity is for castingbig-end-down ingots,

12. The ingot mold of claim 7 wherein the upper portion of said moldcavity is defined by side Walls and relatively shorter end walls, theexothermic side boards being secured along said side walls. 13. An ingotmold having an open end mold cavity for casting metal ingots, means forincreasing ingot yields comprising, a pair of substantially exothermicsideboards secured to said ingot mold along opposed inner surfaces ofthe upper portion of the -mold cavity and on opposite sides of thepouring area of the mold, bare surface areas on the inner surface of themold between said sideboards, and a granular material selected from thegroup consisting of insulating substances and heat producing substancesin said mold cavity on the top of said metal ingot to reduce loss ofheat from the top of the mold.

14. An ingot mold having an open end mold cavity for castingbig-end-down metal ingots, said mold cavity being defined by side wallsand `relatively shorter end walls, means for increasing ingot yieldscomprising, a pair of substantially exothermic sideboards secured tosaid ingot mold along opposed inner surfaces of the upper portion ofsaid side walls and on opposite sides of References Cited UNITED STATESPATENTS 2/ 1960 Edmonds et al. 249-201X 12/1954 Simpson 287-58X FOREIGNPATENTS 10/1904 France.

1914 Great Britain.

OTHER REFERENCES The Iron Age (Publication) Sept. 12, 1957, p. 123 lorelied upon, 22-147A.

J. SPENCER OVERHOLSER, Primary Examiner.

R. D. BALDWIN, Assistant Examiner.

Marburg 249-198 Marburg 249-197 Marburg.

NouVeaW 164-159 15 Vallak 249-197 249-200 U.S. Cl. X.R.

7. AN INGOT MOLD HAVING AN OPEN END MOLD CAVITY FOR CASTING METALINGOTS, MEANS FOR INCREASING INGOT YIELDS COMPRISING, A PAIR OFSUBSTANTIALLY EXOTHERMIC SIDE BOARDS SECURED TO SAID INGOT MOLD ALONGOPPOSED INNER SURFACES OF THE UPPER PORTION OF THE MOLD CAVITY AND ONOPPOSITE SIDES OF THE POURING AREA OF THE MOLD, AND BARE SURFACE AREASON THE INNER SURFACE OF THE MOLD BETWEEN SAID SIDE BOARDS.